Metal cylinder head gasket without a spacing layer

ABSTRACT

One aspect of the invention relates to a cylinder head gasket provided with at least one opening corresponding to a combustion chamber of an internal combustion engine. The gasket has a function layer with a full bead and an annular support with a bead. The bead of the annular support is arranged on the side of the full bead which is oriented away from the combustion chamber. Another aspect of the invention relates to a cylinder head gasket having an upper functional layer, an annular support and a lower functional layer. The annular support is arranged between the upper and lower functional layers and is adjacent to the lower functional layer. The upper functional layer comprises one full bead, and the lower functional layer has a bead arranged on the side of the full bead which is oriented away from the combustion chamber.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application which claims priority toU.S. application Ser. No. 10/583,535, filed Jun. 3, 2009, PCTApplication Serial No. PCT/EP2004/010628, filed Sep. 22, 2004, andGerman Patent Application No. 103 58 919.8, filed Dec. 16, 2003, all ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a metallic cylinder head gasket withouta spacing layer. In particular, it concerns a cylinder head gasket withonly one functional layer.

2. Related Art

A cylinder head gasket ensures impermeability to gas between thecylinder block and cylinder head. Thereby, the cylinder head gasket mustbalance elastic vibrations between the cylinder head and cylinder block.

The functional principle of metallic gaskets for cylinder head use ininternal combustion engines is that an elastic sealing zone is present.The gasket is designed with beads, which form elastic sealing zonesaround the area of the combustion chamber. The pressure of the beadadjusts constantly in the operation of the engine based upon the varyingstress. The strength of the material layer and also the particularmolding of the bead has influence on the elastic properties of the bead,i.e. the elasticity or spring stiffness. The corresponding stress-straincharacteristics can only be varied over a narrow area. The area of sucha gasket directly surrounding the combustion chamber is exposed tohigher stresses during the operation of the engine. To guarantee anadequate sealing in these exposed areas it is necessary to apply a highsurface pressure. This is usually achieved by increasing the materialstrength at the boundary of the combustion chamber, and can be effectedby the crimping of a metal layer or by the use of additional layerswhich are joined with a metal layer of the gasket. Frequently thisthickness of material is arranged so that the beads are protectedbeforehand in the built-in state, to be completely flattened by thepressure.

Cylinder head gaskets usually consist of several layers and also anannular support designated as a stopper. For the increase of pressure inthe areas intensely affected, the beads are provided around thecombustion chamber, which increases the material thickness.

DE 101 01 604 A1 describes a cylinder head gasket with two sealinglayers, one a spacing layer and one an annular support. With thisgasket, the main bead is provided with additional supporting beads inthe sealing layer, near the combustion chamber.

DE 100 29 352 A1 discloses a gasket in which a metal ring is welded to ametal layer along a welding bead, so that the metal ring and metal layerare kept in a spaced apart relationship to one another. While thisgasket has a high impermeability to gas for reason of the welding, theelasticity is reduced due to the firm connection and fixed spacing.

DE 197 51 293 A1 describes a gasket in which a turned-over foldconstitutes a pressure confinement for the bead. Thereby, it forms anarea of higher pressure. But here the bead is held in indirect forceclosure, so that the maximum pressure occurs not in the area of thebead, but in the area of the crimping. This sealing principle isfollowed for diesel engines.

As a rule, a varying construction is used with gasoline engines ofpassenger cars, whereby the pressure on a boundary is eliminated. Here,the combustion chamber is surrounded only by the beads of the cylinderhead gasket, which are flattened in the built-in state. The beads liehere in a direct force fit and thereby receive the maximum pressure.

In this location an uncoiling with great oscillation amplitude takesplace with stress, that is, upon impact of pressure through thecombustion passage into the combustion chamber. With a conventionalgasket it progresses to strong vertical oscillations. Nevertheless, inorder for an adequate impermeability to gas to be ensured, a highpressure is generated against the bead. If the bead positioned in directforce fit is not supported, and thus endures the entire stress, thelifetime of the gasket is thereby negatively influenced.

In EP 0574166 B1 a combination of both forms of construction isdisclosed. A gasket is described which includes a support ring, which inthe built-in state reaches up to full bead of the sealing layer. In thisarrangement the bead lies in direct force fit. This arrangement isparticularly suitable for engines in which the bridge width betweenindividual combustion chambers is small, and a concentration of themaximum pressure upon the area bordering the combustion chamber ispossible.

This support ring follows in its form the profile of the bead, and doesnot outreach the crest of the bead. Thereby, the spring characteristicof the bead is influenced such that the bead becomes harder and alsoloses elasticity. In the built-in state an extreme pressure peak alsoprevails in the area of the crest of the bead. In comparison with abended beam construction, the support ring, to all intents and purposes,constitutes the support point. With the impact of pressure an uncoilingeffect over the crest of the bead develops, which leads to highoscillation amplitudes in the vertical direction. This effect canintensify, depending upon pressure in the combustion chamber.

A support ring designated as a stopper serves to enlarge the materialthickness in the area of the bead and thereby the pressure is raised atthe most stressed positions of the gasket.

The more layers are used, the more complex and therefore the moreexpensive the manufacture of a corresponding cylinder gasket head willbecome. The adjustment of the different layers to one another, and thepossible different temperature dependent expansions signify a potentialdeterioration of the sealing properties and lifetime of thecorresponding gasket.

SUMMARY OF THE INVENTION

It is the goal of the present invention to provide a cylinder headgasket with which the uncoiling effect can be reduced. Another object isto provide a cylinder head gasket which has only one functional layer.

According to a first aspect of the present invention, a metalliccylinder head gasket with at least one through-hole corresponding to acombustion chamber of an internal combustion engine is provided. Thegasket comprises one functional layer and one support ring, whereby thesupport ring is arranged around the through-hole. The functional layercomprises one full bead. The support ring has a full bead on which thefunctional layer rests, and also a bead, which is arranged behind thefull bead when viewed in the radial direction of the opening for thecombustion chamber. This additional bead receives a portion of thepressure which is in effect in the built-in state of the cylinder headgasket.

It is preferred that the bead be implemented as a half bead. This may bea desirable option in order to bring a certain surface into contact withthe bead. Moreover, the elasticity of the bead when formed as a fullbead as compared with that of a half bead, can be adjusted.

It is preferred that the support ring extend from one bead foot at leastup to the other bead foot of the full bead. Thereby, the full bead liesin a direct force fit.

According to another aspect of the invention, a metallic cylinder headgasket with at least one through-hole corresponding to the combustionchamber of an internal combustion engine is provided. The gasketcomprises an upper functional layer, a support ring and a lowerfunctional layer. The support ring is between the upper and lowerfunctional layers, and is arranged around the opening. The upperfunctional layer comprises a full bead. The lower functional layercomprises a bead, which is arranged behind the full bead when viewed inthe radial direction from the opening for the combustion chamber. Theadditional bead receives a portion of the pressure which is in effect inthe built-in state of the cylinder head gasket.

It is preferred that the bead be implemented as a half bead. Theadvantages of this embodiment have already been mentioned.

It is preferred that the half bead be constructed as directed above.Depending upon the alignment, another surface can come into contact withthe appropriate layer. This can affect the properties of the gasket indesirable ways.

It is preferred that the half bead be formed downwards in direction. Itis preferred that the bead be implemented as a full bead. The advantagesof this embodiment have already been mentioned.

It is preferred that the full bead be formed upwards in direction.

It is preferred that the full bead be formed downwards in direction.

It is preferred that the support ring extend from one bead foot at leastup to the other bead foot of the full bead. Thereby, the full bead liesin a direct force fit.

It is preferred that the support ring extend at least from the bead footof the full bead, which is next to the combustion chamber, up to thebead foot of the bead, which is next to the combustion chamber. Thereby,a higher rigidity of the gasket is achieved, and the pressuredistributes over a larger surface.

In the present invention an additional bead is provided in radialdirection behind the combustion chamber. This bead, which can beimplemented as a half bead or a full bead, accepts a portion of thepressure. Since the bead situated next to the combustion chamber mustnot accept the entire stress any longer, the bead tip and/or contact tipcan be optimized in the pressure. Likewise, the second bead accepts anadditional sealing function. These properties improve the sealingproperties and have a positive influence on the lifetime of the cylinderhead gasket.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a and 1 b show two preferred embodiments of a cylinder headgasket according to the invention having one functional layer, in across-sectional view.

FIGS. 2 a and 2 b show preferred embodiments of a multi-layered cylinderhead gasket according to the invention in a cross-sectional view.

FIGS. 3 a and 3 b show other preferred embodiments of a multi-layeredcylinder head gasket according to the invention in a cross-sectionalview.

DETAILED DESCRIPTION OF THE ENABLING EMBODIMENTS

On the left side of each figure one finds the area adjacent to thecombustion chamber of the cylinder head gasket, while on the right sideof each figure is the side oriented away from the combustion chamber.

The bead also rests upon the support ring and/or stopper. This principleis therefore designated as “bead on stopper”. In FIG. 1 a a cylinderhead gasket is shown, which comprises a functional layer 2 and a ringlining 4. The functional layer 2 comprises a full bead 6. The ringlining 4 comprises a full bead 8, in which rests the full bead 6, and ahalf bead 10 lying behind it as viewed in radial direction from thecombustion chamber. In the area designated as A, in which the full bead6 of the functional layer 2 rests upon the ring lining 4, occurs thegreatest pressure in the built-in state. A portion of the pressurearising is absorbed by the half bead 10 of the ring lining 4 in the areadesignated as B, whereby the full bead 6 is relieved. Thereby, anadditional support is also created. The full bead 6 of the functionallayer lies upon the support ring and thus is in direct force contact.The support point of the full bead 6 is also, for all intents andpurposes, the support point of a bended-beam construction.

In FIG. 1 b a modification of the cylinder head gasket is shown. Buthere, instead of the half bead 10 another full bead 12 is formed. Incomparison with the situation shown in FIG. 1 a, here a portion of thepressure in Area C is absorbed by the additional bead. The design of theadditional bead as full bead 12 as shown here or as shown in FIG. 1 a asa half bead enables adjustment of the elastic properties of the cylinderhead gasket of the invention in the area of the additional bead.Thereby, influence is also possible as to which surface the ring supportbehind this area will directly rest upon, which here are either thefunctional layer or as in FIG. 1 the upper side of the cylinder block(not shown).

In FIG. 2 a a multi-layered cylinder head gasket is shown, comprising anupper functional layer 2, a support ring 4 and a lower functional layer14. The upper functional layer 2 comprises a full bead 6, which restsupon ring support 4. The lower functional layer 14 comprises a half bead16 lying behind it when viewed in a radial direction from the combustionchamber. The half bead 16 is formed in the upward direction. Supportring 4 extends from the bead foot of the full bead 6, which is next tothe combustion chamber, up to the bead foot of half bead 16, which isnext to the combustion chamber (in the figure, respectively, on the leftside).

FIG. 2 b displays a modification of the cylinder head gasket of FIG. 2a, in which the half bead 16 is directed downward of lower functionallayer 14.

FIGS. 3 a and 3 b exhibit respective embodiments of a multi-layeredcylinder head gasket according to the invention. In contrast to FIGS. 2a and 2 b the lower functional layer 14 comprises a full bead 18 insteadof a half bead. FIG. 3 a displays an embodiment in which full bead 18 isdirected upward, and FIG. 3 b is another embodiment in which full bead18 is formed downward.

What is claimed is:
 1. A metallic cylinder head gasket with at least oneopening corresponding to a combustion chamber of an internal combustionengine, comprising an upper functional layer, a support ring and a lowerfunctional layer, wherein said support ring is arranged between saidupper functional layer and said lower functional layer and is adjacentto said lower functional layer, said upper functional layer includes afull bead which is adjacent to said support ring, and said lowerfunctional layer including at least one further bead which is arrangedon the side of the full bead oriented away from the said at least saidone opening corresponding to the combustion chamber, wherein said atleast one further bead comprises a half bead, wherein said half bead isso formed, that said lower functional layer lies on the side of saidhalf bead oriented away from said at least said one openingcorresponding to the combustion chamber on a level higher than on theside of said half bead oriented towards said at least said one openingcorresponding to the combustion chamber.
 2. Cylinder head gasketaccording to claim 1, wherein said lower functional layer on the side ofsaid half bead oriented away from said at least said one openingcorresponding to the combustion chamber is spaced at a predetermineddistance from said upper functional layer.
 3. Cylinder head gasketaccording to claim 1, wherein said half bead is so formed, that it isequal in height to said support ring.
 4. Cylinder head gasket accordingto claim 1, wherein said support ring extends from a bead foot of saidfull bead of said upper functional layer oriented towards said at leastone opening corresponding to the combustion chamber up to a bead foot ofsaid at least one further bead oriented towards said at least oneopening corresponding to the combustion chamber.
 5. A metallic cylinderhead gasket with at least one opening corresponding to a combustionchamber of an internal combustion engine, comprising an upper functionallayer, a support ring and a lower functional layer, wherein said supportring is arranged between said upper functional layer and said lowerfunctional layer and is adjacent to said lower functional layer, saidupper functional layer includes a full bead which is adjacent to saidsupport ring, and said lower functional layer including at least onefurther bead which is arranged on the side of the full bead orientedaway from the said at least said one opening corresponding to thecombustion chamber, wherein said at least one further bead comprises afull bead, wherein said lower functional layer is spaced at apredetermined distance from said upper functional layer, and whereinsaid support ring extends from a bead foot of said full bead of saidupper functional layer oriented towards said at least one openingcorresponding to the combustion chamber up to and ends at a bead foot ofsaid at least one further bead oriented towards said at least oneopening corresponding to the combustion chamber.
 6. Cylinder head gasketaccording to claim 5, wherein said further bead in form of said fullbead is so formed, that said lower functional layer lies on the side ofsaid further bead in form of said full bead oriented away from said atleast said one opening corresponding to the combustion chamber on thesame level as on the side oriented towards said at least said oneopening corresponding to the combustion chamber.
 7. Cylinder head gasketaccording to claim 5, wherein a tip of said full bead is directeddownwards.
 8. Cylinder head gasket according to claim 5, wherein a tipof said full bead is directed upwards.